Dataset Information

Functional Modulation of Regulatory T Cells by IL-2.

ABSTRACT: The suppressive function of regulatory T cells (Tregs) is critical to the maintenance of immune homeostasis in vivo and yet, the specific identification of Tregs by phenotypic markers is not perfect. Tregs were originally identified in the CD4+CD25+ fraction of T cells, but FoxP3 expression was later included as an additional marker of Tregs as FoxP3 expression was identified as being critical to the development and function of these cells. Intracellular expression of FoxP3 makes it difficult in using to isolate live and not permeabilized cells for functional assays. As such CD4+CD25+ fraction is still frequently used for functional assays of Tregs. Although, the CD4+CD25+ fraction substantially overlaps with the FoxP3+ fraction, the minor mismatch between CD4+CD25+ and FoxP3+ fractions may confound the functional characteristics of Tregs. In this study, we isolated CD4+FoxP3+ as well as CD4+CD25+ fractions from Foxp3 knock-in mice, and compared their proliferative and suppressive activity in the presence or absence of various concentrations of IL-2. Our results showed comparable patterns of proliferative and suppressive responses for both fractions, except that contrary to the CD4+CD25+ fraction the FoxP3+ fraction did not proliferate in an autocrine fashion even in response to a strong stimulation. In presence of exogenous IL-2, both CD4+CD25+ and CD4+FoxP3+ fractions were more sensitive than the CD4+CD25- responder cells in proliferative responsiveness. In addition, a low dose IL-2 enhanced whereas a high dose abrogated the suppressive activities of the CD4+CD25+ and CD4+FoxP3+ fractions. These results may provide an additional understanding of the characteristics of the various fractions of isolated Tregs based on phenotype and function and the role of varying levels of exogenous IL-2 on the suppressive activity of these cells.

SUBMITTER: Moon BI

PROVIDER: S-EPMC4631326 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Functional Modulation of Regulatory T Cells by IL-2.

Moon Byung-In BI Kim Tae Hun TH Seoh Ju-Young JY

PloS one 20151103 11

The suppressive function of regulatory T cells (Tregs) is critical to the maintenance of immune homeostasis in vivo and yet, the specific identification of Tregs by phenotypic markers is not perfect. Tregs were originally identified in the CD4+CD25+ fraction of T cells, but FoxP3 expression was later included as an additional marker of Tregs as FoxP3 expression was identified as being critical to the development and function of these cells. Intracellular expression of FoxP3 makes it difficult in ...[more]

PMID: 26529512

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Project description:Background: Stroke patients are at risk of acquiring secondary infections due to stroke-induced immune suppression (SIIS). Immunosuppressive cells comprise myeloid-derived suppressor cells (MDSCs) and immunosuppressive interleukin 10 (IL-10)-producing monocytes. MDSCs represent a small but heterogeneous population of monocytic, polymorphonuclear (or granulocytic), and early progenitor cells ("early" MDSC), which can expand extensively in pathophysiological conditions. MDSCs have been shown to exert strong immune-suppressive effects. The role of IL-10-producing immunosuppressive monocytes after stroke has not been investigated, but monocytes are impaired in oxidative burst and downregulate human leukocyte antigen-DR isotype (HLA-DR) on the cell surface. Objectives: The objective of this work was to investigate the regulation and function of MDSCs as well as the immunosuppressive IL-10-producing monocytes in experimental and human stroke. Methods: This longitudinal, monocentric, non-interventional prospective explorative study used multicolor flow cytometry to identify MDSC subpopulations and IL-10 expression in monocytes in the peripheral blood of 19 healthy controls and 27 patients on days 1, 3, and 5 post-stroke. Quantification of intracellular STAT3p and Arginase-1 by geometric mean fluorescence intensity was used to assess the functionality of MDSCs. In experimental stroke induced by electrocoagulation in middle-aged mice, monocytic (CD11b+Ly6G-Ly6Chigh) and polymorphonuclear (CD11b+Ly6G+Ly6Clow) MDSCs in the spleen were analyzed by flow cytometry. Results: Compared to the controls, stroke patients showed a relative increase in monocytic MDSCs (percentage of CD11b+ cells) in whole blood without evidence for an altered function. The other MDSC subgroups did not differ from the control. Also, in experimental stroke, monocytic, and in addition, polymorphonuclear MDSCs were increased. The numbers of IL-10-positive monocytes did not differ between the patients and controls. However, we provide a new insight into monocytic function post-stroke since we can report that a differential regulation of HLA-DR and PD-L1 was found depending on the IL-10 production of monocytes. IL-10-positive monocytes are more activated post-stroke, as indicated by their increased HLA-DR expression. Conclusions: MDSC and IL-10+ monocytes can induce immunosuppression within days after stroke.

Project description:UnlabelledRegulatory T cells (Treg ) suppress T effector cell proliferation and maintain immune homeostasis. Autoimmune liver diseases persist despite high frequencies of Treg in the liver, suggesting that the local hepatic microenvironment might affect Treg stability, survival, and function. We hypothesized that interactions between Treg and endothelial cells during recruitment and then with epithelial cells within the liver affect Treg stability, survival, and function. To model this, we explored the function of Treg after migration through human hepatic sinusoidal-endothelium (postendothelial migrated Treg [PEM Treg ]) and the effect of subsequent interactions with cholangiocytes and local proinflammatory cytokines on survival and stability of Treg . Our findings suggest that the intrahepatic microenvironment is highly enriched with proinflammatory cytokines but deficient in the Treg survival cytokine interleukin (IL)-2. Migration through endothelium into a model mimicking the inflamed liver microenvironment did not affect Treg stability; however, functional capacity was reduced. Furthermore, the addition of exogenous IL-2 enhanced PEM Treg phosphorylated STAT5 signaling compared with PEMCD8. CD4 and CD8 T cells are the main source of IL-2 in the inflamed liver. Liver-infiltrating Treg reside close to bile ducts and coculture with cholangiocytes or their supernatants induced preferential apoptosis of Treg compared with CD8 effector cells. Treg from diseased livers expressed high levels of CD95, and their apoptosis was inhibited by IL-2 or blockade of CD95.ConclusionRecruitment through endothelium does not impair Treg stability, but a proinflammatory microenvironment deficient in IL-2 leads to impaired function and increased susceptibility of Treg to epithelial cell-induced Fas-mediated apoptosis. These results provide a mechanism to explain Treg dysfunction in inflamed tissues and suggest that IL-2 supplementation, particularly if used in conjunction with Treg therapy, could restore immune homeostasis in inflammatory and autoimmune liver disease. (Hepatology 2016;64:138-150).

Dataset Information

Functional Modulation of Regulatory T Cells by IL-2.

Publications

Functional Modulation of Regulatory T Cells by IL-2.

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